A process for the manufacture of a composite structure, known from the state of the art and illustrated in FIG. 1, comprises the following stages:                a) Providing a donor substrate 1 comprising a first surface 2, and a support substrate 3;        b) Forming a zone of weakening 4 in the donor substrate 1, the zone of weakening 4 delimiting, with the first surface 2 of the donor substrate 1, a working layer 5;        c) Assembling the support substrate 3 and the donor substrate 1;        d) Fracturing the donor substrate along the zone of weakening, so as to transfer the working layer 5 onto the support substrate 3;        e) Thinning the working layer 5 so as to obtain a thinned working layer 6.        
However, the main disadvantage related to this manufacturing process of the state of the art is that the thinned working layer 6 exhibits a nonuniformity in thickness. This is because the thinning stage e) generally comprises a stage of partial oxidation of the working layer 5, followed by a withdrawal of the oxidized part of the working layer 5.
The oxidation partially oxidizes the working layer 5 over a nonuniform thickness. Thus, this is reflected by a variation in thickness of the thinned working layer 6 after withdrawal of the oxidized part of the working layer 5. The variation of thickness of the thinned working layer 6 can exceed 10 Å on conclusion of all of the stages.
This is, in particular, damaging for the manufacture of structures of the silicon-on-insulator type, for which control of the variation of thickness of the silicon layer to +/−5 Å is required.
The control of the thickness of the thinned working layer 6 on conclusion of all of the stages of the manufacturing process thus remains very difficult.
An aim of the disclosure is thus to provide a process for the manufacture of structures that makes possible better control of the variation of thickness of the thinned working layer 6.